1. Field of the Invention
The present invention relates to a control system and method of a vehicular continuously variable transmission having a manual transmission mechanism and more specifically to a modification in the manual transmission mechanism thereof.
2. Prior Art
The continuously variable transmission is generally employed as an automatic transmission capable of changing a speed ratio (transmission ratio) automatically, however it has also a capability of changing a speed ratio by manual operation like a manual transmission. Japanese Patent Application Laid-open No. Toku-Kai-Hei 6-58399 discloses a continuously variable transmission in which a vehicle driver can establish the speed ratio arbitrarily by manual operation. Further, International Patent Application No. PCT/EP 92/01155 discloses a technique I in which a vehicle driver can select a desired speed range (or speed ratio) among several predetermined speed ratios (6 speed ranges) by manual operation.
However, the prior art described above, for example, the technique disclosed in Toku-Kai-Hei 6-58399 involves a problem that it is difficult for the vehicle driver to foresee what degree of acceleration or deceleration is obtained from the speed ratio arbitrarily selected when manually operated. On the other hand, in case of selecting a desired speed range among predetermined fixed speed ranges, this technique is still unsatisfactory from the aspect of power performance and it has a problem that the vehicle driver feels a substantial degree of shift-shock if he or she forgets to perform shift changes.